A stack of 400μ Ilford G-5 nuclear emulsion surrounded by 5.5 cm of brass was flown at 85 000 feet for 10 hours at $\lambda =41\mathrm{}°$N. While scanning 409 ${\mathrm{cm}}^2$ of these emulsions the decay of seven $K$ particles and one $\tau$ meson have been observed. A hyperon produced in a star is seen to decay into an $L$ meson. For the decay scheme $Y^{\pm }\to {\pi }^{\pm }+n+Q$ this event gives $Q=(48\mathrm{}\pm 20)$ Mev. A heavy nuclear fragment ($Z\sim 5$) from an eight-prong star decays into ${\mathrm{Li}}^8$, a proton, and a particle that is probably a deuteron. An event has been observed that could be interpreted as an example of the decay of a $\tau$ meson by the decay scheme ${\tau }^{+}\to {\pi }^{+}+2\mathrm{}{\pi }^0$.

• Received 18 February 1954

DOI:https://doi.org/10.1103/PhysRev.94.1328